绝对值不大于3的所有整数的积等于______．
绝对值不大于3的所有整数有：0，±1，±2，±3，
∴它们的积为0．
故答案为0．
-----Who helped ________with the job ?
-----Nobody , They did it by______.
A．them, them
B．them, themselves
C．themselves, them
D．themselves, themselves
引起传染病的细菌、病毒和寄生虫等生物，称为 。
